Muffler



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llll l llll f l \l lllll'llllll'll'l ll I I I 3 a MW; e N V F I y IUnited States Patent Ofifice 3,087,580 Patented Apr. 30, 1963 3,937,580MUFFLER Waiter H. Powers and Benton D. Jacokes, Jackson, Mich,

assignors to Walker Manufacturing Company, Racine,

Wis, a corporation of Delaware Continuation of application Ser. No.551,043, Dec. 5, 1955. This application Oct. 12, 1959, Ser. No. 845,888

2 Claims. (Cl. 181-61) This application is a continuation of ourcopending application, Serial No. 551,043, filed December 5, 1955, nowabandoned.

This invention relates to mothers and, in particular, to casings formufilers of the type ordinarily used in exhaust systems for automobilesand trucks.

It is the object of this invention to stiffen the casing of mufflers bymeans of ribs which can be readily formed therein in the manufacturingprocess. The ribs tend to stiffen the casing and make it possible toreduce the amount of metal used to obtain proper strength and they alsotend to reduce vibrations of the muffler shell itself.

We accomplish this and other objects by means of a construction in whichthe ribs are arranged at angles to each other, preferably transverselyand longitudinally of the muffler. The ribs are formed in such a waythat they can be easily added to the shell or casing in the course ofmanufacture of the muffler.

A preferred construction embodying the principles of our invention isshown in the accompanying drawings in which:

FIGURE 1 is a side elevation of a mufiler embodying the invention;

FIG. 2 is an enlarged cross section taken along the line 2--2 of FIG. 1;

FIG. 3 is an enlarged view of an intersection of the transverse,longitudinal ribs as taken within the circle 3 of FIGURE 1;

FIG. 4 is an enlarged end elevation taken from the left of FIG. 1;

FIG. 5 is a cross section through the mufller taken along the line 5-5of FIG. 4;

FIG. 6 is a cross section taken along the line 6-6 of FIG. 5;

FIG. 7 is a cross section taken along the line 7--7 of FIG. 5; and

FIG. 8 is an end elevation taken from the right of FIG. 5.

As shown in FIGURE 1, the muffler 1 includes a casing 3 which isinterlocked at 5 with the end headers 7 and 9 to form a closed interior.Within the casing 3 is silencing structure of a suitable designincluding an inlet bushing 11 and an outlet bushing formed in the outletheader 9. A series of partitions 17, 19, 21, 23, and divide the spacewithin the casing 3 into a series of chambers 27, 29, 51, 33, 35, and37. The inlet bushing 11 supports an end of the perforated inlet tube 12and the other end of the tube is supported in a flanged opening in thepartition 19. The end of the tube 12 also has a slide fit with aperforated continuation tube 39, the other end of which tube issupported in a flanged opening in the partition 23. Supported in thepartitions 21 and 23, in flanged openings therein, is a perforatedreturn tube 41. A perforated outlet tube 43 is supported at its innerend in a flanged opening in partition 21 and by means ofcircumferentially spaced embossments on its outer surface in a flangedopening in the partition 25, as shown at 45. The tubes 12 and 4-3 have aseries of louvers or openings formed therein and located around theseopenings is a pancake construction consisting of split shells 47, thehalves of which have flanges. vthat are secured together as shown at 49.These quency spit chambers to attenuate sounds in the exhaust gases. Thetubes 39 and 41 also have suitable openings or louvers formed thereinwhich open into the chamber 33. The chamber 33 and the chamber 35 areconnected by the flanged opening 50 in partition 23 around pancakesection 47 (FIG. 6). The tube 13 has lower openings formed thereinopening into a chamber 37, these openings being the only outlet to saidchamber so that it acts as a resonator chamber. Mounted in thepartitions 17 and 19 is an imperforate tube 53 which connects chamber 31with chamber 27. Chamber 27 is connected with chamber 29 by means ofopenings 57 in the partition 17 so it will be seen that chambers 27 and29 form a compound resonator construction receiving gas from the chamber31.

Gas will enter the inlet bushing 11 and flow through the tube 12 intothe tube 39 and thence through the crossover chamber 35 into the tube41. From the tube 41 they will enter cross-over chamber 31 and then tube43 and pass out of the muffler through the bushing 15. The pancakeassemblies 47 around tube 12 and tube 43 will remove high frequencysounds. Other frequencies in gas passing through tubes 39 and 41 will beremoved in chamber 33, and the opening Stl between chambers 33 and 35will suppress further noise. Lower frequencies will be removed incompound resonator chambers 27 and 29 which reached through tuning tube53 and still other low frequencies can be removed in resonator chamber37.

Turning now to the construction of the casing 3, it will be seen that itpreferably comprises an oval-shaped, double wrapped layer or" originallyfiat metal which is wrapped around twice and then interlocked by spotwelding in a three-layer joint shown at 71. The muffier thereforecomprises an oval-shaped piece of material that is wrapped around itselfinto two layers and then spot welded in an overlapped joint consistingof three layers. This is done, of course, prior to the insertion of thevarious silencing elements and prior to attachment of the end heads 7and 9. While it is in this oval open-ended condition, and the sidesthereof are plain or blank, the longitudinal ribs and the transverseribs 77 are formed in both layers of metal as clearly seen in FIGS. 2,6, and 7. These ribs extend outwardly, that is, they constitute raisedsurfaces on the outside of the casing 3 and the transverse ribs 77terminate inwardly of the sides 78 of the casing. This arrangement haspeculiar advantages insofar as practical manufacture of the casing isconcerned. They are formed by passing about one-half the length of thecasing 3 over a male die which is thus on the inside and which containsridges or ribs on its outer surface corresponding to the ribs 75 and 77.The inner die is enough smaller than the minor width or diameter of thecasing 3 to permit spring back of the metal to substantially lift thecasing oh. the die and the ribs thereon. A female outer die is thenbrought into engagement with the outer surface of the casing 3 so as topress it down over the ribs against the inner die member. It wouldnormally be expected that difliculty would be encountered in removingthe inner die member after the formation of such ribs. However, we havefound that the spring back of the metal in combination with theshortened length of transverse ribs '77 is enough to enable the casing 3to be readily removed from the inner die. We contemplate forming theribs in only about half of the length of the casing at a time and inorder to insure alignment when the casing is turned end for end to formribs in the other half, we preferably provide the circular enlargements79 at the inner ends of at least one of the longitudinal ribs 75. Whenthe ribs are then formed in the other end, it is a simple matter toalign the ends of the ribs 75' with the circular portion 79 and thussecure proper alignment.

It will be noted that the ribs 77 do not extend over the full width ofthe mufiler. Thus there are no ribs on the die near the sides 78 andspring back of the flatter and relatively flexible central portions 80of the casing will lift the casing off the die so that it can be removedfrom the die after ribs 75' and 77 are formed in it. The longitudinalribs 75 preferably terminate inwardly of the ends of the casing so asnot to provide stiffness in the bands at the end of the casing whichwill be turned around and interlocked in the joint 5 with the endheaders 7 and 9. The intersection of the ribs 75 and 77 is provided withsuitable radii '78 as shown in FIGURE 3.

It will now be seen that we have provided an improved mufiler casingwherein readily formed ribs are provided to overcome drumming of thecasing and that changes can be made in the specific structure shownherein without departing from the spirit and scope of the invention.

We claim:

1. In a muffler for internal combustion engines, an elongated tubularone piece casing of oval cross section and open at opposite ends, headermeans closing the ends of the casing, the outside of the casing definingthe external surface of the mufiler and the inside of the easingdefining the inside surface of the mufiler and an inside chamber, gassilencing means in said inside chamher, said casing having alongitudinal axis and said oval cross section having a major axis and aminor axis, said casing having a pair of opposite major sides subtendedby said major axis and a pair of opposite minor sides subtended by saidminor axis, said major sides being wide and rather flat and capable ofspring back and subject to vibrations by acoustical pressure vibrationsinside the casing, stiffening and anti-vibration means for said majorsides to prevent drumming and adapted to be formed therein when said onepiece casing is tubular and openended, said stiffening means comprisinga series of longitudinally spaced transverse ribs formed in each majorside to extend transversely of said longitudinal axis and projectoutwardly of the casing beyond said external sur face, said transverseribs being substantially shorter than the width of the major sides andterminating inwardly of the side edges of the major sides, saidstiffening means also including two transversely spaced, parallel,longitudinally extending ribs formed in each major side to projectoutwardly of said casing beyond said external surface and intersect allof said transverse ribs.

2, The invention set forth in claim 1 wherein said longitudinal ribsterminate inwardly of the opposite ends of the casing to leave unribbedbands at said opposite ends, said header means comprising a pair ofheaders at each end of the casing interlocked in a reversely bent jointwith portions of said unribbed bands at the ends of the casing.

References Cited in the file of this patent UNITED STATES PATENTS1,186,572 Guibert June 13, 1916 1,376,957 MacKenzie et al. May 3, 19211,656,629 Gray Jan. '17, 1928 1,815,005 Hamilton et a1. July 14, 19312,277,132 Moss Mar. 24, 1942 2,607,331 Wefing Aug. 19, 1952 2,656,005Cary Oct. 20, 1953 2,661,073 Deremer Dec. 1, 1953 2,835,336 Deremer May20, 1958 2,902,109 Burgess et al Sept. 1, 1959 FOREIGN PATENTS 221,071Great Britain Sept. 4, 1924 124,755 Australia July 10, 1957

1. IN A MUFFLER FOR INTERNAL COMBUSTION ENGINES, AN ELONGATED TUBULARONE PIECE CASING OF OVAL CROSS SECTION AND OPEN AT OPPOSITE ENDS, HEADERMEANS CLOSING THE ENDS OF THE CASING, THE OUTSIDE OF THE CASING DEFININGTHE EXTERNAL SURFACE OF THE MUFFLER AND THE INSIDE OF THE CASINGDEFINING THE INSIDE SURFACE OF THE MUFFLER AND AN INSIDE CHAMBER, GASSILENCING MEANS IN SAID INSIDE CHAMBER, SAID CASING HAVING ALONGITUDINAL AXIS AND SAID OVAL CROSS SECTION HAVING A MAJOR AXIS AND AMINOR AXIS, SAID CASING HAVING A PAIR OF OPPOSITE MAJOR SIDES SUBTENDEDBY SAID MAJOR AXIS AND A PAIR OF OPPOSITE MINOR SIDES SUBTENDED BY SAIDMINOR AXIS, SAID MAJOR SIDES BEING WIDE AND RATHER FLAT AND CAPABLE OFSPRING BACK AND SUBJECT TO VIBRATIONS BY ACOUSTICAL PRESSURE VIBRATIONSINSIDE THE CASING, STIFFENING AND ANTI-VIBRATION MEANS FOR SAID MAJORSIDES TO PREVENT DRUMMING AND ADAPTED TO BE FORMED THEREIN WHEN SAID ONEPIECE CASING IS TUBULAR AND OPENENDED, SAID STIFFENING MEANS COMPRISINGA SERIES OF LONGITUDINALLY SPACED TRANSVERSE RIBS FORMED IN EACH MAJORSIDE TO EXTEND TRANSVERSELY OF SAID LONGITUDINAL AXIS AND PROJECTOUTWARDLY OF THE CASING BEYOND SAID EXTERNAL SURFACE, SAID TRANSVERSELYRIBS BEING SUBSTANTIALLY SHORTER THAN THE WIDTH OF THE MAJOR SIDES ANDTERMINATING INWARDLY OF THE SIDE EDGES OF THE MAJOR SIDES, SAIDSTIFFENING MEANS ALSO INCLUDING TWO TRANSVERSELY SPACED, PARALLEL,LONGITUDINALLY EXTENDING RIBS FORMED IN EACH MAJOR SIDE TO PROJECTOUTWARDLY OF SAID CASING BEYOND SAID EXTERNAL SURFACE AND INTERSECT ALLOF SAID TRANSVERSE RIBS.